1. Technical Field
The present invention is directed toward pullers, and more particularly toward pullers usable in removing an object from a shaft.
2. Background Art
Pullers used in grasping an object secured to a shaft and pulling the object off of the shaft are known in the art. Typically, such pullers include a plurality of clamped jaws which are located about the object with grasping ends of the jaws engaging the object to be removed from the shaft. A central pusher element will be driven against the end of the shaft to pull the jaws and clamped object over and off of the shaft.
For example, one type of such structure which has been widely used has manually positionable jaws which are maintained in position grasping an object principally by the frictional forces generated at their grasping ends by the stresses of pulling. Such structures have included jaws which are pivotally supported at an intermediate point with the non-grasping end bearing against a shoulder. Other such structures have included jaws pivoted at one end with a plurality of intermediate links manually adjustable by moving a central link collar to locate the jaws. However, the jaws in such structures can slip during use, such slipping being a significant disadvantage in several respects. First, slipping of the puller obviously results in wasted time and general inefficiency of use. Also, due to the large forces typically being applied when pulling an object tightly wedged on a shaft, slipping during use can result in backlash with obvious danger to the individual operating the puller. Still further, such backlash can damage not only the puller itself, but also the object being removed from the shaft. Of course, damage to the object being removed can leave it in a condition in which it is much more difficult to finish removing it from the shaft.
Other such structures which have been used include a separate clamp which physically connects the jaws together at a selected position. However, such structures are not readily usable with large pullers or with pullers having more than two jaws.
Still another structure which has been used has been to provide a cage around the outside of the jaws to restrain their outward movement. Such pullers are shown, for example, in U.S. Pat. Nos. 4,007,535 and 4,068,365. Of course, such pullers can only be used in removing objects which can be grasped around their outer perimeter. Further, the cages of such pullers have been found to be susceptible to breaking when they are subjected to high forces, particularly when such structures are used with larger objects (relative to the puller size) due to the large stresses resulting from the geometry of the puller. Still further, while such jaws are generally retained against completely slipping off of the object being grasped, the jaws are nevertheless susceptible to some amounts of slipping. As previously described, such slipping can have numerous undesirable effects, including damage to the object, damage to the puller, and injury to the operator.
The present invention is directed toward overcoming one or more of the problems set forth above.